1. Field
The present disclosure relates generally to the capability of an aircraft moving on a runway to slow down and come to a stop. More particularly, the present disclosure relates to a system and method for predicting the stopping position of an aircraft moving on a runway, displaying the predicted stopping position to an operator of the aircraft, and providing a warning when the aircraft is predicted to overrun the runway.
2. Background
An aircraft may be moving at a relatively fast speed immediately after landing on a runway. Such a fast moving aircraft must be slowed down in order for the aircraft to exit the runway safely via a taxiway. More importantly, the aircraft must be slowed down at a sufficient rate so that the aircraft may be brought to a stop or exit the runway safely via a taxiway before the aircraft overruns the end of the runway.
A pilot or other operator of an aircraft may control various systems on the aircraft to slow down and stop an aircraft moving on a runway. Aircraft systems that may be used for bringing a moving aircraft to a stop on a runway may include an aircraft braking system, the aircraft thrust system, and the aerodynamic system of the aircraft. The aircraft braking system may be controlled by the pilot or automatically to slow the rotation of the aircraft wheels as the wheels roll on the runway. The aircraft thrust system may be controlled to slow the aircraft by controlling the aircraft engines to provide thrust in an appropriate direction to slow the movement of the aircraft. The aerodynamic system of the aircraft may include, for example, a speed brake, flaps, other systems, or various combinations of systems that may be controlled to change the aerodynamic characteristics of the aircraft. The aerodynamic system of the aircraft may be controlled to slow the aircraft by increasing drag and lift reduction to destroy the lift of the wing of the aircraft as it moves on the runway.
The capability of the various systems on an aircraft to slow down and stop the aircraft moving on a runway may depend on various conditions. For example, the condition of the runway may affect the ability of the aircraft braking system to stop the aircraft. The ability of the aircraft braking system to stop an aircraft moving on a runway is reduced when the force of friction between the wheels of the aircraft and the surface of the runway is reduced. Therefore, for example, the capability of the braking system on an aircraft to stop the aircraft moving on a runway may be reduced when the runway is icy or wet.
A pilot or other operator of an aircraft may rely on experience, a judgment of runway conditions, and a judgment of the capability of various aircraft systems to stop the aircraft under such conditions, to control the various systems on the aircraft to stop the aircraft moving on the runway. The pilot may be provided with information from various sources that may help the pilot to judge the current condition of the runway. For example, the pilot may be provided with data from airport friction measuring devices, weather reports, or other information that may help the pilot to judge the current condition of the runway prior to landing. However, even with the availability of such information, a pilot may not always be able to judge accurately either the current runway condition or the effects of the current runway condition on aircraft stopping performance. For example, runway conditions may change relatively quickly.
Therefore, a pilot or other operator of an aircraft may not be able to rely on experience and reported condition alone to stop an aircraft moving on a runway effectively under all conditions and to prevent the aircraft from overrunning the end of the runway. Experience and judgment alone may not be sufficient for a pilot or other operator of an aircraft to control various systems on the aircraft to stop the aircraft moving on a runway in an effective manner. For example, a pilot may not be able to judge accurately the condition of the runway and the effect of the runway condition on the operation of the braking system on the aircraft. As a result, the pilot may not be able to discern accurately the current deceleration of the aircraft or whether the current deceleration will slow the aircraft enough to exit the runway safely via a desired taxiway or to stop before overrunning the runway.
Automated systems for determining a predicted stopping position of an aircraft moving on a runway have been developed. Such systems may provide an indication of the predicted stopping position of the aircraft to the pilot or other operator of the aircraft. Such systems also may provide an audible warning or other warning when the predicted stopping position of the aircraft indicates that the aircraft may overrun the runway.
Current automated systems for indicating a predicted stopping position of an aircraft moving on a runway and for providing overrun warnings may have several limitations. For example, current automated systems may not be able to predict the stopping position of the aircraft accurately for various runway conditions and operating conditions of the various aircraft systems that may be used to stop an aircraft moving on a runway. Therefore, current systems may provide an inaccurate indication of the predicted stopping position of the aircraft and incorrect warnings for when the aircraft is predicted to overrun the runway in some cases. For example, such systems may provide inappropriate overrun warnings in many cases where it is likely that the aircraft will stop in time or be able to exit the runway safely via a taxiway before overrunning the runway.
Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.